<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>图标字体</title>

    <!--<link href="css/bootstrap.min.css" rel="stylesheet">-->
    <link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css">
</head>
<body>
   <div class="container">
       <h5>1.如何使用</h5>
       <!--
        1.必须使用cdn的方式引入库;
        2.不要和其他组件混合使用,单独用一个span标签来承载图标字体.
        3.只对内容为空的元素起作用(图标类只能应用在不包含任何文本内容或子元素的元素上).
        4.图标的可访问性(aria-hidden="true").
       -->
       <span class="glyphicon glyphicon-heart" aria-hidden="true"></span><br>

       <button class="btn btn-primary btn-lg">
           <span class="glyphicon glyphicon-user" aria-hidden="true"></span>
       </button>

       <div class="alert alert-danger" role="alert">
           <span class="glyphicon glyphicon-exclamation-sign" aria-hidden="true"></span>
           <span class="sr-only">Error:</span>
           Enter a valid email address
       </div>




   </div>
</body>
</html>